Remember, you need a different type of switch for battery and magneto ignitions because they have different operating principles. A battery ignition uses an external power source to create the spark at the spark plug. It is usually a 12-volt battery and an external coil. The switch controls the voltage to the coil via the “I” terminal. When the switch is in an “on” position, it sends 12 volts to the coil. When it is in the “off” position, it doesn’t send volts to the coil and will not allow it to create a spark.